Resolving the gap between laboratory and field rates of feldspar weathering

Gruber, Chen; Zhu, Chen; Georg, R. Bastian; Zakon, Yevgeni; Ganor, Jiwchar

doi:10.1016/j.gca.2014.10.013

Cited by 42 publications

(23 citation statements)

References 63 publications

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“…The progressive evolution of the surface area during the dissolution process and the impact of these physicochemical changes on dissolution rates should be taken into account to develop more realistic dissolution models (Lüttge et al, 2013). Recent studies showing that the structural anisotropy of a mineral induces changes in terms of surface area and reactivity during the dissolution process are nice illustrations of this assertion (Bandstra and Brantley, 2008;Daval et al, 2013;Godinho et al, 2014a, Gruber et al, 2014Pollet-Villard et al, 2016a, b). The demonstration of the impact of various energy surface sites (dislocations, kink and step sites for minerals, differently coordinated Si surface groups for glasses) on dissolution rates is also a good example (Dove et al, 2008;Fischer et al, 2014;Pollet-Villard et al, 2016;Godinho et al, 2014a).…”

Section: Introductionmentioning

confidence: 99%

Comparing the reactivity of glasses with their crystalline equivalents: The case study of plagioclase feldspar

Pérez

Daval

Fournier

et al. 2019

Geochimica et Cosmochimica Acta

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To evaluate the impact of atomic short-and long-range orders on silicate dissolution kinetics, the dissolution of amorphous and crystalline albite was investigated at pH 1.5 and 10 at 90°C. Experiments in solution saturated with respect to SiO2 am were additionally performed to constrain the effect of Si-rich surface layer formation on dissolution rates. The face-specific dissolution rates of the crystalline albite and of the albite glass were determined from element budget in solution and surface retreat measured by vertical scanning interferometry. The results show that atomic ordering primarily impacts solid reactivity, irrespective to the pH of the solution. A strong relation between the crystal surface orientation, the evolution of its topography and its dissolution rate was observed. The (001), (010) and (10-1) flat faces containing the strongest bonds dissolved the most slowly and their dissolution rates remained constant throughout the experiments. In contrast, the stepped (1-11) face was characterized by the highest initial dissolution rate, but progressively decreased, suggesting that the preferential dissolution of stepped sites expose afterwards more stable planes. The differences in terms of etch pit density from one surface to another also allowed to explain the difference in dissolution rates for the (001) and (010) faces. The fluid chemistry suggested the formation of very thin (100-200 nm) Si-rich surface layers in acidic conditions, which weakly affected the dissolution rate of the pristine crystal. At pH 1.5, albite glass dissolves at a rate similar to that of the fastest studied faces of the crystal. Whereas Si-rich surface layers likely formed by interfacial dissolution-reprecipitation for albite crystal, molecular dynamic calculations suggest that the open structure of the glass could also allow ion-exchange following water diffusion into the solid. This different mechanism could explain why the surface layer of the glass is characterized by a different chemical composition. Results at pH 10 are strikingly different, as the albite glass dissolves 50 times faster than its crystalline equivalent. This non-linear response of the material upon pH was linked to the density of critical bonds in albite which is indeed pH-dependent. In acidic pH, the preferential dissolution of Al leaves a highly polymerized and relaxed Si-rich surface, whereas in basic pH the preferential dissolution of Si leads to a complete de-structuration of the network because of the lack of Si-O-Al bonds.

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Section: Introductionmentioning

confidence: 99%

Comparing the reactivity of glasses with their crystalline equivalents: The case study of plagioclase feldspar

Pérez

Daval

Fournier

et al. 2019

Geochimica et Cosmochimica Acta

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“…The obtained weathering rates of silicate minerals from field samples can vary by multiple orders of magnitude from experimentally obtained rates, with the latter usually being higher (White et al, 2001;White and Brantley, 2003;Brantley, 2005;Zhu et al, 2006;Moore et al, 2012). This indicates the complexity of dissolution mechanisms in nature as well as the inability to measure dissolution rates under these complex conditions and time scales in the laboratory (Gruber et al, 2014). Hellmann et al (2012) concluded that chemical weathering of silicate minerals is controlled by nanoscale interfacial https://doi.org/10.5194/se-2020-34 Preprint.…”

Section: Introductionmentioning

confidence: 98%

Quartz dissolution associated with magnesium silicate hydrate cement precipitation

Ruiter¹,

Gunnæs²,

Dysthe³

et al. 2020

Preprint

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Abstract. Quartz has been replaced by magnesium silicate hydrate cement at the Feragen ultramafic body in south-east Norway. This occurs in deformed and recrystallized quartz grains deposited as glacial till covering part of the ultramafic body. Where the ultramafic body is exposed, weathering leads to high pH (~10), Mg-rich fluids. The dissolution rate of the quartz is about 3 orders of magnitude higher than experimentally derived rate equations suggest under the prevailing conditions. Quartz dissolution and cement precipitation starts at intergranular grain boundaries that act as fluid pathways through the recrystallized quartz. Etch pits are also extensively present at the quartz surfaces as result of preferential dissolution at dislocation sites. Transmission electron microscopy revealed an amorphous silica layer with a thickness of 100–200 nm around weathered quartz grains. We suggest that the amorphous silica is a product of interface-coupled dissolution-precipitation and that the amorphous silica subsequently reacts with the Mg-rich, high pH bulk fluid to precipitate magnesium silicate hydrate cement, allowing for further quartz dissolution and locally a complete replacement of quartz by cement. The cement is the natural equivalent of magnesium silicate hydrate cement (M-S-H), which is currently of interest for nuclear waste encapsulation or for environmentally friendly building cement, but not yet developed for commercial use. This study provides new insights that could potentially contribute in the further development of M-S-H cement.

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“…For instance, several types of indirect field measurement approaches were combined to yield estimates of in-situ mineral weathering rates (Ackerer et al, 2016;Ferrier et al, 2010). In parallel, mineral dissolution kinetics were evaluated in the laboratory by monitoring dissolution rates against controlled parameters, such as T, pH or ∆ (Carroll and Knauss, 2005;Gruber et al, 2014;Hellmann and Tisserand, 2006). This framework allowed to build up databases of parameters used in semi-empirical mineral weathering rate laws (Palandri and Kharaka, 2004;Rimstidt et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

In-situ dissolution rates of silicate minerals and associated bacterial communities in the critical zone (Strengbach catchment, France)

Wild

Daval

Beaulieu

et al. 2019

Geochimica et Cosmochimica Acta

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Weathering of silicate minerals in the Critical Zone (CZ) is fundamental for numerous environmental and societal issues. Despite decades of efforts to accurately record biogeochemical variables controlling mineral reactivity in the field and to reproduce them in the laboratory, weathering rates estimates still differ from those observed in natural settings.Here we examine the biogeochemical environment of mineral surfaces exposed to contrasted weathering conditions in various compartments of a temperate CZ (Strengbach observatory, France). A novel approach was developed to probe both in-situ mineral dissolution rates and bacterial diversity associated to mineral surfaces. Labradorite and olivine minerals were either buried in the A and C horizons of a soil profile, directly exposed to meteoric fluids or immersed in stream water. Dissolution rates recorded in the soil profile were up to 2 orders of magnitude slower than those predicted using a numerical weathering model. Samples directly exposed to meteoric fluids exhibited contrasted dissolution rates that could not be explained by simple abiotic weathering, while dissolution rates of samples incubated in stream water were particularly low. In soil profiles, the field-laboratory discrepancy by up to 2 orders of magnitude was attributed to heterogeneity of fluid circulation and local variation of reaction conditions.Mineral substrates changed bacterial communities of the mineralosphere after 9 and 20 months of incubation in the CZ. However, we observed that this effect could be delayed or driven by extrinsic factors. Although mineral probes in soil horizons were enriched in bacterial phylotypes potentially involved in mineral weathering (e.g., Pseudomonas sp., Collimonas sp., Burkholderia sp., Janthinobacterium sp., Leifsonia sp., and Arthrobacter sp.), the relative contribution of biotic weathering could not be quantified in-situ. Altogether, the heterogeneity of in-situ mineral dissolution rates in key compartments of the CZ reveals the crucial need to improve spatial characterization of hydrogeochemical properties at the soil profile scale, and to evaluate the quantitative role of microbial communities to mineral weathering.

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Resolving the gap between laboratory and field rates of feldspar weathering

Cited by 42 publications

References 63 publications

Comparing the reactivity of glasses with their crystalline equivalents: The case study of plagioclase feldspar

Comparing the reactivity of glasses with their crystalline equivalents: The case study of plagioclase feldspar

Quartz dissolution associated with magnesium silicate hydrate cement precipitation

In-situ dissolution rates of silicate minerals and associated bacterial communities in the critical zone (Strengbach catchment, France)

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